Injured Cronulla fullback Nathan Gardner says he's determined to make it back on the field before the NRL finals and fight for his No.1 jersey.

The Sharks have signed Penrith star Michael Gordon for next season, who has indicated in the past his preferred position is fullback.

Gardner is desperate to get his knee right to assist the Sharks on their premiership charge, but to also stake an early claim for a starting spot next year.

"It was my third year playing fullback this year so I definitely want to keep my spot," Gardner told AAP.

"And if I'm not back this year I'll just have to make sure I rip in during the pre-season and hopefully I can stay in the No.1.

"I've got to do everything in my power and the rest looks after itself."

Gardner, who comes off contract at the Sharks at the end of next season, says the comeback trail from injury has been painful and mentally draining - and made even tougher by the Sharks' excellent form.

Cronulla are sailing along nicely in third place on the ladder, but Gardner believes he can add an x-factor to their playoff ambitions should he get himself right.

"I'd like to think so. I'd like to think I've proven and shown what I can do," he said.

"Even if it's not to be and I don't make it back, if I'm out on the training field putting pressure on the boys so they're looking over their backs at me, I suppose that would be a positive for the team as well.

"You hear about guys doing their knees and they're out for the whole season but now the physio has dangled a little carrot in front of me.

"It just gives me that little bit extra to work towards and hopefully I will be back."